Species richness and biodiversity significance of alpine micro-waterbody systems in Gaoligong Mountain, Northwest Yunnan, China

Simple SummaryMayflies are among the most susceptible insect groups in mountain freshwater bodies, where they are facing different environmental threats, resulting in loss of species assemblage and diversity. In this study, we described the structure of the community of mayflies in three different streams in the dry-hot valley of Baima Snow Mountain, China, and assessed the potential effect of environmental variation over this specific group of insects. The results showed clear shifts in the community structure of mayflies between the streams. From the study area, 18 taxa were identified, with Baetis sp. and Baetiella marginata being the most prevalent. Overall, the Yeri stream hosted suitable habitats for several taxa of mayflies than the other two streams, as demonstrated by the highest species richness and diversity. Moreover, there was high environmental heterogeneity between the streams, in turn influencing the species of mayflies, particularly in the Sharong stream. As expected, the results also showed that some of the environmental factors such as altitude, conductivity, total dissolved solids, water temperature, dissolved silicon, and pH explained most of the variation in species composition.Mountain freshwater ecosystems are threatened all over the world by a range of human-induced stresses, ensuing in a rapid loss of habitats and species diversity. Many macroinvertebrates are reactive to habitat disturbance, and mayflies (Ephemeroptera) are amongst the most sensitive groups. Despite they are susceptible to environmental deviation, knowledge concerning their species richness and diversity is still unknown in remote areas. The objectives of this study were to (1) investigate the mayfly species assemblage and community composition along different mountain streams and assess potential differences, and (2) identify the environmental variation and its influence on the structure of mayfly communities within such freshwater systems. We collected biological and environmental data from 35 sites situated along elevation gradients in the Baima Snow Mountain, northwest Yunnan, China. Multivariate analyses were performed on the environmental variables and the mayfly species composition, as well as on richness and diversity indices. We found that the community composition of mayflies was different across all three watercourses. Among the 18 Ephemeroptera taxa identified, Baetis sp. and Baetiella marginata were highly dominant, accounting for over 50% of the dissimilarity of each stream. In terms of species assemblages, almost all sites in the Yeri stream hosted good-quality habitats for several mayfly species, as reflected by the highest species richness. The Benzilan stream followed, whereas the Sharong stream showed relatively low mayfly assemblage. This variation was explained by the high environmental heterogeneity between the three watercourses. In particular, the RDA model revealed that among the different environmental factors analyzed, altitude, conductivity, total dissolved solids, water temperature, dissolved silicon, and pH explained most of the variation in species composition. Moreover, the altitude alone explained 17.74% of the variation, and in-depth analysis confirmed its significant effect on diversity indices. Further research should focus on evaluating the scale of threats to this important group of insects in the mountain freshwater ecosystem, particularly the impact of human-induced disturbances such as land use/landcover alterations.

Ecological interactions are widely distributed in nature and can affect the diversification and maintenance of the global biodiversity. In this dissertation, we evaluated how several ecological variables affect the intensity of mutualistic interactions between ants and plants with extrafloral nectaries (EFNs), how such interactions affect and are affected by associative interactions between Cerrado plants, and, at last, we performed a comprehensive review aiming to quantify the impact of associative effects among plants in a broader sense. In the first chapter, we evaluated the effects of ant nest distribution and richness, in addition to the potential effects caused by the presence of neighboring plant species with EFNs, on a liana plant from the Brazilian Cerrado, Smilax Polyantha. We sampled ant nests and neighboring plants with EFNs around each S. polyantha, and measured its foliar herbivory and fruit production. We observed that higher densities of ant nests contributed to a reduction of foliar herbivory and to increases in fruit production. However, higher ant nest richness was associated with higher foliar herbivory values, while the diversity of neighboring plants was associated with reductions in herbivory and fruit production. The effects of ant nest distribution were, thus, antagonistic. In the second chapter, we tested the associative effects between S. polyantha and support plants on the herbivory and fruit production of S. polyantha. We measured foliar herbivory, fluctuating asymmetry, and the fruit production of S. polyantha, and we verified the presence of EFNs in support plant species. Smilax polyantha individuals associated with plants with EFNs were more visited by ants and had lower herbivory and fluctuating asymmetry. Plants with EFNs can, thus, benefit closely distributed plants and possibly impact the structuring of plant communities. In the third chapter, we performed an extensive quali-quantitative review about associative resistance (AR) between plants. We initially performed a historical review regarding the AR term, and then we conducted a quantitative review. We gathered data from studies on online databases and used meta-analytical tools to identify and measure the main mechanisms behind AR and measure them against a series of ecological variables (e.g., plant traits, and spatial variables). At last, we discuss the patterns found and their implications for biological control practices and the structuring of communities. We conclude that the intensity and direction of ecological interactions rely not only on the directly involved species, but on the surrounding ecological context. In the current global scenario, preserving plant biodiversity is essential since it is associated with the maintenance of biodiversity as a whole.

Mexico has higher mammalian diversity than expected for its size and geographic position. High environmental hetero geneity throughout Mexico is hypothesized to promote high turnover rates (β‐diversity), thus contributing more to observed species richness and composition than within‐habitat (α) diversity. This is true if species are strongly associated with their environments, such that changes in environmental attributes will result in changes in species composition. Also, greater heterogeneity in an area will result in greater species richness. This hypothesis has been deemed false for bats, as their ability to fly would reduce opportunities for habitat specialization. If so, we would expect no significant relationships between 1) species composition and environmental variables, 2) species richness and environmental heterogeneity, 3) β‐diversity and environmental heterogeneity. We tested these predictions using 31 bat assemblages distributed across Mexico. Using variance partitioning we evaluated the relative contribution of vegetation, climate, elevation, horizontal heterogeneity (a variate including vegetation, climate, and elevational heterogeneity), spatial variation (lat‐long), and vertical hetero geneity (of vegetation strata) to variation in bat species composition and richness. Variation in vegetation explained 92% of the variation in species composition and was correlated with all other variables examined, indicating that bats respond directly to habitat composition and structure. Beta‐diversity and vegetational heterogeneity were significantly correlated. Bat species richness was significantly correlated with vertical, but not horizontal, heterogeneity. Nonetheless, neither horizontal nor vertical heterogeneity were random; both were related to latitude and to elevation. Variation in bat community composition and richness in Mexico were primarily explained by local landscape heterogeneity and environmental factors. Significant relationships between β‐diversity and environmental variation reveal differences in habitat specialization by bats, and explain their high diversity in Mexico. Understanding mechanisms acting along environmental or geographic gradients is as important for understanding spatial variation in community composition as studying mechanisms that operate at local scales.

AimMapping the geographic distribution of non-native aquatic species is a critically important precursor to understanding the anthropogenic and environmental factors that drive freshwater biological invasions. Such efforts are often limited to local scales and/or to single species, due to the challenges of data acquisition at larger scales. Here, we map the distribution of non-native freshwater species richness across the continental United States and investigate the role of human activity in driving macro-scale patterns of aquatic invasion.LocationThe continental United States.MethodsWe assembled maps of non-native aquatic species richness by compiling occurrence data on exotic animal and plant species from publicly accessible databases. Using a dasymetric model of human population density and a spatially explicit model of recreational freshwater fishing demand, we analysed the effect of these metrics of human influence on the degree of invasion at the watershed scale, while controlling for spatial and sampling bias. We also assessed the effects that a temporal mismatch between occurrence data (collected since 1815) and cross-sectional predictors (developed using 2010 data) may have on model fit.ResultsNon-native aquatic species richness exhibits a highly patchy distribution, with hotspots in the Northeast, Great Lakes, Florida, and human population centres on the Pacific coast. These richness patterns are correlated with population density, but are much more strongly predicted by patterns of recreational fishing demand. These relationships are strengthened by temporal matching of datasets and are robust to corrections for sampling effort.Main conclusionsDistributions of aquatic non-native species across the continental US are better predicted by freshwater recreational fishing than by human population density. This suggests that observed patterns are driven by a mechanistic link between recreational activity and aquatic non-native species richness and are not merely the outcome of sampling bias associated with human population density.

AimStudying species richness patterns by considering all species as equivalent units may prevent a deeper understanding of the origin and maintenance of biodiversity. Here, we deconstructed the species richness of Neotropical lianas by specific attributes of species to study richness–environment relationships.LocationNeotropics.TaxonTribe Bignonieae (Bignoniaceae), the largest clade of Neotropical lianas.MethodsWe used five morphological, one geographical and two evolutionary attributes of species, each with 2–7 attribute states. We compared the environmental response of species richness of each attribute state to the response of overall Bignonieae species richness. For those groups of species that differed in their environmental response to three‐dimensional habitat structure, climate and soil we assessed: (a) the magnitude and direction of the environmental response; and (b) the variation in species richness explained by environmental variables and spatial filters using variation partitioning analysis.ResultsWe identified eight attribute states whose richness–environment relationship differed from the overall richness pattern: three morphological (species with shrubby habit, lacking tendrils and with seeds bearing ellipsoid wings), three geographical (species with small, small‐to‐medium and medium‐to‐large range sizes) and two evolutionary (species of the generaAmphilophiumandCuspidaria) attribute states. Areas with high species richness of these eight attribute states did not overlap with the centres of Neotropical diversity in the tribe Bignonieae. A high fraction of the variation in species richness of these eight attribute states was accounted for by spatial filters or remained unexplained.Main conclusionsThe richness deconstruction approach revealed that richness–environment relationships of species with specific attribute states differ from the overall species richness pattern. These morphological, geographical and evolutionary attribute states are mostly related to the survival and persistence in savanna habitats, and show that ecological strategies and evolutionary histories need to be taken into account to fully understand richness–environment relationships.

Imagine a hypothetical scenario. Imagine you are traveling through space and come across Earth for the first time ... what would you be most struck by? Would it be the water that gives our planet the nickname ‘blue-marble’? I doubt it. We’ve now found water on the moon (Saal et al., 2008), on several other planets in our own solar system (Carr et al., 1998; Malin and Edgett, 2000), and a single survey of the Milky Way found >270 planets in the so-called “habitable zone,” warm enough for liquid water (Borucki et al., 2011). Would you instead be struck by the mountains, canyons and other geological features that are most visible from space? Again, it’s doubtful. Geologists tell us there are few, if any, landforms that are wholly unique to Earth (Baker, 2008; Dietrich and Perron, 2006), and you probably would have seen them all before. Based on our current understanding of the universe, the only thing a space-traveler is likely to be struck by, and the one thing that appears to be fundamentally unique to Earth, is its remarkable variety of life. Ever since the first prokaryotic cells evolved more than 3 billion years ago, the diversity of life on Earth has steadily increased, punctuated by only a handful of extinction events. Our best guess is there are perhaps 9 million forms of eukaryotic organisms on this planet (Mora et al., 2011). The number of prokaryotic organisms is largely unknown, but a single hydrothermal vent on the bottom of the ocean can harbor an astounding 37,000 unique types of microbes (Huber et al., 2007). While the great variety of life is perhaps the most striking feature of Earth, loss of this biodiversity is one of the most striking forms of environmental change in the Anthopocene. The percentage of species that have gone extinct ranges from just < 1% to 13% of described taxa depending on the group considered (Barnosky et al., 2011). But rates of extinction are occurring orders of magnitude faster than what is ‘normal’ in the fossil record. Projections suggest that if these high rates of extinction continue, biodiversity loss could equal or exceed the five prior mass extinctions (loss of 75% or more of known taxa) in 240 to 540 years (Barnosky et al., 2011). So what? What does it matter if we lose 75% of all life forms on the planet over the next few centuries? Will Earth become any less hospitable for humans? Will this planet still be able provide people with the food, water, air, and other goods and services needed to survive and prosper? Won’t evolution simply replace all of that lost diversity with life forms that are more fit for a human dominated planet? And if evolution does compensate for extinctions in the Anthropocene, what ecological roles will those newly evolved species play? These are pressing questions as we ponder what future Earth will be like. The variety of life that has evolved over 3.6-billion years is a catalog of biological resources from which we produce nearly all of the goods and services needed for humanity to prosper (Daily et al., 1997; MEA, 2005; Cardinale et al., 2012). If we are to have any hope of predicting how human domination of the planet will impact our own prosperity in an era that will have fewer biological options, we must develop a general theory of Earth’s biodiversity that can predict both the causes as well as the consequences of biological variation. Fortunately, biologists have made great strides on developing models that simultaneously explain three dimensions of biodiversity: (a) the evolutionary origin of biodiversity, (b) the ecological maintenance of biodiversity, and (c) the ecosystem-level function of biodiversity. Below I describe one set of evolutionary and ecological models that are beginning to show remarkably consistency in form. These models are by no means the only descriptions of how diversity originates, why species coexist, or how diversity influences ecosystem function. But the particular models discussed here do have a common thread that suggests biologists from different sub-disciplines are, in some instances, converging on a suite of equations, all with similar terms that collectively predict the origin, maintenance, and function of biodiversity. Domain Editor-in-Chief Donald R. Zak, University of Michigan

A component of metabolic scaling theory has worked towards understanding the influence of metabolism over the generation and maintenance of biodiversity. Specific models within this 'metabolic theory of biodiversity' (MTB) have addressed temperature gradients in speciation rate and species richness, but the scope of MTB has been questioned because of empirical departures from model predictions. In this study, we first show that a generalized MTB is not inconsistent with empirical patterns and subsequently implement an eco-evolutionary MTB which has thus far only been discussed qualitatively. More specifically, we combine a functional trait (body mass) approach and an environmental gradient (temperature) with a dynamic eco-evolutionary model that builds on the current MTB. Our approach uniquely accounts for feedbacks between ecological interactions (size-dependent competition and predation) and evolutionary rates (speciation and extinction). We investigate a simple example in which temperature influences mutation rate, and show that this single effect leads to dynamic temperature gradients in macroevolutionary rates and community structure. Early in community evolution, temperature strongly influences speciation and both speciation and extinction strongly influence species richness. Through time, niche structure evolves, speciation and extinction rates fall, and species richness becomes increasingly independent of temperature. However, significant temperature-richness gradients may persist within emergent functional (trophic) groups, especially when niche breadths are wide. Thus, there is a strong signal of both history and ecological interactions on patterns of species richness across temperature gradients. More generally, the successful implementation of an eco-evolutionary MTB opens the perspective that a process-based MTB can continue to emerge through further development of metabolic models that are explicit in terms of functional traits and environmental gradients.

Abstract. The study was conducted in deciduous forests of two Swedish regions, Öland and Uppland. It had two objectives: to (1) test the species pool hypothesis by examining if differences in small‐scale species richness are related to differences in large‐scale species richness and the size of the regional species pool, and (2) to examine the relationship between species richness and productivity and its scale‐dependence.The first data set comprised 36 sites of moderate to high productivity. In each site, we recorded the presence of vascular plant species in nested plots ranging from 0.001 to 1000 m2 and measured several environmental variables. Soil pH and Ellenberg site indicator scores for nitrogen were used as estimators of productivity. The second data set included 24 transects (each with 20 1‐m2 plots) on Öland in sites with low to high productivity. Species number, soil pH and relative light intensity were determined in each plot. The forest sites on Öland were more species‐rich than the Uppland sites on all spatial scales, although environmental conditions were similar. Small‐scale and large‐scale species richness were positively correlated. The results present evidence in favour of the species pool hypothesis. In the nested‐plots data set, species number was negatively correlated with pH and nitrogen indicator scores, whereas a unimodal relationship between species number and pH was found for the transect data set. These results, as well as previously published data, support the hump‐shaped relationship between species richness and productivity in Swedish deciduous forests. Two explanations for the higher species richness of the sites with moderate productivity are given: first, these sites have a higher environmental heterogeneity and second, they have a larger ‘habitat‐specific’ species pool.

Stand structure and species composition and diversity are the essential characteristics of ecological communities and often related to ecosystem processes and functions. However, these characteristics of the tropical cloud forests in Hainan Island are still poorly studied. This chapter aimed to fill this gap to a certain degree, paving the way for further revealing species coexistence and biodiversity maintenance. Based on the plots established in Bawangling, we compared the community structure and species composition and diversity of the two different types of TCF: tropical montane evergreen forests (TMEF) and tropical montane dwarf forests (TMDF). We found that the Sørensen index between them was 0.71. In both TMEF and TMDF, Lauraceae was the most dominant family, while Rubiaceae and Fagaceae were also the dominant families. TMDF was characterized by strong species monodominance that the importance value of Distylium racemosum was larger than 10, while TMEF was dominated by 5 species (Syzygium araiocladum, Distylium racemosum, Cyclobalanopsis disciformis, Psychotria rubra, and Syzygium buxifolium) with the importance values ranging from 5.20 to 7.12. Compared with TMDF, TMEF showed low stem abundance but high values of species richness, bootstrap estimator, and first and second Jackknife estimators. The logistic model provided better fits on the species accumulation curves of TMEF and TMDF than the power-law and exponential models. In general, trees in TMEF showed significant higher values of the mean height and diameter at breast height but lower stem density than those in TMDF. Our results indicate a high similarity in species composition and the significant differences in species diversity and community structure between TMDF and TMEF. Such differences could be attributed to environmental conditions.KeywordsStand structureSpecies compositionPlant diversityTropical cloud forest

Abstract. The study was conducted in deciduous forests of two Swedish regions, Öland and Uppland. It had two objectives: to (1) test the species pool hypothesis by examining if differences in small-scale species richness are related to differences in large-scale species richness and the size of the regional species pool, and (2) to examine the relationship between species richness and productivity and its scale-dependence. The first data set comprised 36 sites of moderate to high productivity. In each site, we recorded the presence of vascular plant species in nested plots ranging from 0.001 to 1000 m2 and measured several environmental variables. Soil pH and Ellenberg site indicator scores for nitrogen were used as estimators of productivity. The second data set included 24 transects (each with 20 1-m2 plots) on Öland in sites with low to high productivity. Species number, soil pH and relative light intensity were determined in each plot. The forest sites on Öland were more species-rich than the Uppland sites on all spatial scales, although environmental conditions were similar. Small-scale and large-scale species richness were positively correlated. The results present evidence in favour of the species pool hypothesis. In the nested-plots data set, species number was negatively correlated with pH and nitrogen indicator scores, whereas a unimodal relationship between species number and pH was found for the transect data set. These results, as well as previously published data, support the hump-shaped relationship between species richness and productivity in Swedish deciduous forests. Two explanations for the higher species richness of the sites with moderate productivity are given: first, these sites have a higher environmental heterogeneity and second, they have a larger ‘habitat-specific’ species pool.

This study examines the variation in cacti species richness and abundance among sites with different average rainfall and soil types. We assessed a total of 3,660 individuals of six species of Cactaceae: Cereus jamacaru, Melocactus zehntneri, Pilosocereus gounellei, Pilosocereus pachycladus, Tacinga inamoena, and Tacinga palmadora. The greatest species richness and abundance of cacti were at locations with low rainfall and more clayey soils. The species studied differed in multidimensional representation, with some species being more positively related to soils with a higher proportion of fine particles (M. zehntneri and P. gounellei), while others were negatively related to soils with a higher proportion of coarser particles (T. inamoena) or positively related to areas with higher rainfall and vegetation cover (C. jamacaru and P. pachycladus). The differential responses of the species of Cactaceae studied in relation to the gradients analyzed demonstrates the need for more research into the relationship between cacti and environmental variables in semiarid ecosystems with high environmental heterogeneity.

Environmental filtering and spatial structuring are important ecological processes for the generation and maintenance of biodiversity. However, the relative importance of these ecological drivers for multiple facets of diversity is still poorly understood in highland streams. Here, we examined the responses of three facets of stream macroinvertebrate alpha diversity to local environmental, landscape‐climate and spatial factors in a near‐pristine highland riverine ecosystem. Taxonomic (species richness, Shannon diversity, and evenness), functional (functional richness, evenness, divergence, and Rao's Quadratic entropy), and a proxy of phylogenetic alpha diversity (taxonomic distinctness and variation in taxonomic distinctness) were calculated for macroinvertebrate assemblages in 55 stream sites. Then Pearson correlation coefficient was used to explore congruence of indices within and across the three diversity facets. Finally, multiple linear regression models and variation partitioning were employed to identify the relative importance of different ecological drivers of biodiversity. We found most correlations between the diversity indices within the same facet, and between functional richness and species richness were relatively strong. The two phylogenetic diversity indices were quite independent from taxonomic diversity but correlated with functional diversity indices to some extent. Taxonomic and functional diversity were more strongly determined by environmental variables, while phylogenetic diversity was better explained by spatial factors. In terms of environmental variables, habitat‐scale variables describing habitat complexity and water physical features played the primary role in determining the diversity patterns of all three facets, whereas landscape factors appeared less influential. Our findings indicated that both environmental and spatial factors are important ecological drivers for biodiversity patterns of macroinvertebrates in Tibetan streams, although their relative importance was contingent on different facets of diversity. Such findings verified the complementary roles of taxonomic, functional and phylogenetic diversity, and highlighted the importance of comprehensively considering multiple ecological drivers for different facets of diversity in biodiversity assessment.

Aim (1) To explore the impact of land use, climate and environmental heterogeneity on fern species richness along a complete elevational gradient, and (2) to evaluate the relative importance of the three groups of variables within different elevational intervals. Location A temperate mountain region (55,507 km2) of Italy on the southern border of the European Alps divided into a regular grid of 1476 cells (grain 35.7 km2). Methods We applied multiple regression (spatial and non-spatial) to determine the relative influence of the three groups of variables on species richness, including variation partitioning at two scales. We considered the whole gradient (all 1476 cells) to explain the overall elevational pattern of species richness, and we grouped the cells into elevational intervals of 500 m in order to evaluate the explanatory power of the predictors within different zones along the gradient. Results Species richness showed a hump-shaped pattern with elevation, forming a plateau between 800 and 1500 m. The lowest species richness was found in warm and relatively dry disturbed lowlands. Moving upwards, the greatest species richness was found in forest-dominated mid-elevations with high environmental heterogeneity. At high elevations dominated by open natural habitats, where temperature and precipitation were relatively low, species richness declined but less sharply than in the lowlands. Although it was impossible to separate the effects of the three groups of predictors along the whole gradient, the analysis of separate elevational intervals shed light on their relative importance. The decline of species richness within lowlands was mainly related to a combined effect of deforestation and low environmental heterogeneity. In the middle part of the gradient, habitat heterogeneity and topographic roughness were positively associated with species richness. The richness decline within high-elevation areas was related mostly to climatic constraints. Main conclusions Human impact due to land-use modifications strongly affects the elevational pattern of species richness. It is therefore increasingly important to adopt a multiple-hypothesis approach, taking anthropogenic effects explicitly into account when describing ecological processes along elevational gradients.

Understanding the importance of spatial scale in the patterns of grassland invasions

The Altitudinal Atlantic Forest is comprised of humid forest enclaves on top of the mountains surrounded by the Caatinga's xeric shrubland vegetation. It is considered a humidity refuge of endemism in semi-arid regions, and it is under intense anthropogenic pressure. Dung beetle communities are widely used as an ecological indicator of environmental conservation. However, dung beetle communities of the Altitudinal Atlantic Forest are poorly studied, and their value for biodiversity conservation in semi-arid regions is unknown. We describe and compare dung beetle communities of Altitudinal Atlantic Forest remnants located in the Brazilian Northeast semi-arid region to evaluate whether diversity patterns and species composition differ among the remnants. We captured 1,333 beetles belonging to 24 species. Only one remnant showed a statistically significant difference in diversity based on species richness and abundance, and beta diversity showed a high dissimilarity among remnants. The remnants had in common only one species, and the dominant species were distinct among them. Species composition was 16% similar among the sampled remnants, and we registered species commonly found in the Atlantic Forest, the Caatinga, and Amazonia. The structure of the dung beetle community in each remnant could be related to the historical origin and maintenance of the Altitudinal Atlantic Forest. Species compositions changed as a result of geographic location and surrounding environments, which act as filters to dung beetle species flow and establishment. We highlight the importance of the Altitudinal Atlantic Forest for the conservation and maintenance of biodiversity in the semi-arid region.